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1.
The Impact of Morning versus Afternoon Exercise on Iron Absorption in Athletes.
McCormick, R, Moretti, D, McKay, AKA, Laarakkers, CM, Vanswelm, R, Trinder, D, Cox, GR, Zimmerman, MB, Sim, M, Goodman, C, et al
Medicine and science in sports and exercise. 2019;(10):2147-2155
Abstract
PURPOSE This study examined postexercise inflammatory, hepcidin, and iron absorption responses to endurance exercise performed in the morning versus the afternoon. METHODS Sixteen endurance-trained runners (10 male, 6 female) with serum ferritin (sFer) < 50 μg·L completed a 90-min running protocol (65% vV˙O2max) in the morning (AM), or the afternoon (PM), in a crossover design. An iron-fortified fluid labeled with stable iron isotopes (Fe or Fe) was administered with a standardized meal 30 min following the exercise and control conditions during each trial, serving as a breakfast and dinner meal. Venous blood samples were collected before, immediately after, and 3 h after the exercise and control conditions to measure sFer, serum interleukin-6 (IL-6), and serum hepcidin-25. A final venous blood sample was collected 14 d after each trial to determine the erythrocyte iron incorporation, which was used to calculate iron absorption. Linear mixed-modeling was used to analyze the data. RESULTS Overall, exercise significantly increased the concentrations of IL-6 (4.938 pg·mL; P = 0.006), and hepcidin-25 concentrations significantly increased 3 h after exercise by 0.380 nM (P < 0.001). During the PM trial, hepcidin concentrations exhibited diurnal tendency, increasing 0.55 nM at rest (P = 0.007), before further increasing 0.68 nM (P < 0.001) from prerun to 3 h postrun. Fractional iron absorption was significantly greater at breakfast after the AM run, compared with both the rested condition (0.778%; P = 0.020) and dinner in the AM run trial (0.672%; P = 0.011). CONCLUSIONS Although exercise resulted in increased concentrations of IL-6 and hepcidin, iron was best absorbed in the morning after exercise, indicating there may be a transient mechanism during the acute postexercise window to promote iron absorption opposing the homeostatic regulation by serum hepcidin elevations.
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Increasing Iron Status through Dietary Supplementation in Iron-Depleted, Sedentary Women Increases Endurance Performance at Both Near-Maximal and Submaximal Exercise Intensities.
Pompano, LM, Haas, JD
The Journal of nutrition. 2019;(2):231-239
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Abstract
BACKGROUND Iron deficiency persists as the most common micronutrient deficiency globally, despite having known detrimental effects on physical performance. Although iron supplementation and aerobic exercise have been examined individually and are known to improve physical performance, the impact of simultaneous iron supplementation and aerobic training remains unclear. OBJECTIVE The aim of this study was to examine the individual and combined effects of iron supplementation and aerobic training on improving maximal and submaximal physical performance in iron-depleted, nonanemic (IDNA) women. We hypothesized that women receiving iron would improve their endurance performance but not their estimated maximal oxygen consumption (eVO2max). METHODS Seventy-three sedentary, previously untrained IDNA (serum ferritin <25 µg/L and hemoglobin >110 g/L) women aged 18-26 y with a body mass index (kg/m2) of 17-25 participated in a double-blind, 8-wk, randomized controlled trial with a 2 × 2 factorial design including iron supplementation (42 mg elemental Fe/d) or placebo and aerobic exercise training (5 d/wk for 25 min at 75-85% of age-predicted maximum heart rate) or no training. Linear models were used to examine relations between training, supplement, and changes in the primary outcomes of observed maximal oxygen consumption (VO2peak) and eVO2max and ventilatory threshold (absolute oxygen consumption and percentage of maximum). Re-evaluation of a published meta-analysis was used to compare effects of iron supplementation on maximal oxygen consumption (VO2max) and VO2peak. RESULTS There were significant training-by-supplement interactions for VO2peak, volume of oxygen consumption at the ventilatory threshold, and the percentage of eVO2max where the threshold occurred, with the iron-untrained group performing better than the placebo-untrained group. There was no beneficial effect of iron supplementation for VO2max (mean difference: 0.53; 95% CI: -0.75, 1.81; P = 0.42), but a significant benefit was observed for VO2peak (mean difference: 1.87; 95% CI: 0.15, 3.60; P = 0.03). CONCLUSIONS Iron supplementation increases endurance performance at submaximal and maximal (VO2peak) exercise intensities in IDNA women. However, increasing iron status does not increase eVO2max. This trial was registered at clinicaltrials.gov as NCT03002090.
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Caffeine Supplementation Improves Anaerobic Performance and Neuromuscular Efficiency and Fatigue in Olympic-Level Boxers.
San Juan, AF, López-Samanes, Á, Jodra, P, Valenzuela, PL, Rueda, J, Veiga-Herreros, P, Pérez-López, A, Domínguez, R
Nutrients. 2019;(9)
Abstract
BACKGROUND this study examined the effects of caffeine supplementation on anaerobic performance, neuromuscular efficiency and upper and lower extremities fatigue in Olympic-level boxers. METHODS Eight male athletes, members of the Spanish National Olympic Team, were enrolled in the study. In a randomized double-blind, placebo-controlled, counterbalanced, crossover design, the athletes completed 2 test sessions after the intake of caffeine (6 mg·kg-1) or placebo. Sessions involved initial measures of lactate, handgrip and countermovement jump (CMJ) performance, followed by a 30-seconds Wingate test, and then final measures of the previous variables. During the sessions, electromiography (EMG) data were recorded on the gluteus maximus, biceps femoris, vastus lateralis, gastrocnemius lateral head and tibialis anterior. RESULTS caffeine enhanced peak power (6.27%, p < 0.01; Effect Size (ES) = 1.26), mean power (5.21%; p < 0.01; ES = 1.29) and reduced the time needed to reach peak power (-9.91%, p < 0.01; ES = 0.58) in the Wingate test, improved jump height in the CMJ (+2.4 cm, p < 0.01), and improved neuromuscular efficiency at peak power in the vastus lateralis (ES = 1.01) and gluteus maximus (ES = 0.89), and mean power in the vastus lateralis (ES = 0.95) and tibialis anterior (ES = 0.83). CONCLUSIONS in these Olympic-level boxers, caffeine supplementation improved anaerobic performance without affecting EMG activity and fatigue levels in the lower limbs. Further benefits observed were enhanced neuromuscular efficiency in some muscles and improved reaction speed.
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Two-Day Residence at 2500 m to 4300 m Does Not Affect Subsequent Exercise Performance at 4300 m.
Kenefick, RW, Beidleman, BA, Andrew, SP, Cadarette, BS, Muza, SR, Fulco, CS
Medicine and science in sports and exercise. 2019;(4):744-750
Abstract
PURPOSE To determine the efficacy residing for 2 d at various altitudes while sedentary (S) or active (A; ~90 min hiking 2 d) on exercise performance at 4300 m. METHODS Sea-level (SL) resident men (n = 45) and women (n = 21) (mean ± SD; 23 ± 5 yr; 173 ± 9 cm; 73 ± 12 kg; V˙O2peak = 49 ± 7 mL·kg·min) were randomly assigned to a residence group and, S or A within each group: 2500 m (n = 11S, 8A), 3000 m (n = 6S, 12A), 3500 m (n = 6S, 8A), or 4300 m (n = 7S, 8A). Exercise assessments occurred at SL and 4300 m after 2-d residence and consisted of 20 min of steady-state (SS) treadmill walking (45% ± 3% SL V˙O2peak) and a 5-mile, self-paced running time trial (TT). Arterial oxygen saturation (SpO2) and HR were recorded throughout exercise. Resting SpO2 was recorded at SL, at 4 and 46 h of residence, and at 4300 m before exercise assessment. To determine if 2-d altitude residence improved 4300 m TT performance, results were compared with estimated performances using a validated prediction model. RESULTS For all groups, resting SpO2 was reduced (P < 0.01) after 4 h of residence relative to SL inversely to the elevation and did not improve after 46 h. Resting SpO2 (~83%) did not differ among groups at 4300 m. Although SL and 4300 m SS exercise SpO2 (97% ± 2% to 74% ± 4%), HR (123 ± 10 bpm to 140 ± 12 bpm) and TT duration (51 ± 9 to 73 ± 16 min) were different (P < 0.01), responses at 4300 m were similar among all groups, as was actual and predicted 4300 m TT performances (74 ± 12 min). CONCLUSIONS Residing for 2 d at 2500 to 4300 m, with or without daily activity, did not improve resting SpO2, SS exercise responses, or TT performance at 4300 m.
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The Effects of Sodium Phosphate Supplementation on Physiological Responses to Submaximal Exercise and 20 km Cycling Time-Trial Performance.
Brown, JA, Glaister, M
Journal of dietary supplements. 2019;(5):564-575
Abstract
The aim of this study was to examine the effects of sodium phosphate (SP) supplementation on physiological responses to submaximal exercise and 20 km cycling time-trial performance. Using a randomized, double-blind, crossover design, 20 endurance-trained male cyclists (age: 31 ± 6 years; height: 1.82 ± 0.07 m; body mass: 76.3 ± 7.0 kg; maximal oxygen uptake [V̇O2max]: 57.9 ± 5.5 mL·kg-1·min-1) completed two supplementation trials separated by a 14-day washout period. The trials consisted of 10 minutes of cycling at 65% V̇O2max followed by a 20 km time trial. Expired air was monitored throughout each trial for the evaluation of V̇O2, minute ventilation (V̇E), and respiratory exchange ratio (RER). Heart rate was monitored during each trial along with ratings of perceived exertion (RPE) and blood lactate concentration. For four days before each trial, participants ingested 50 mg·kg fat-free mass-1·day-1 of either SP or placebo. There were no effects (p ≥ .05) of supplementation on physiological responses during cycling at 65% V̇O2max. There were also no effects of supplementation on time-trial performance (placebo: 32.8 ± 2.2 min; SP: 32.8 ± 2.3 min). Nevertheless, relative to placebo, SP increased V̇E (mean difference: 3.81 L·min-1; 95% confidence interval: [0.16, 7.46 L·min-1]), RER (mean difference: 0.020; 95% confidence interval: [0.004, 0.036]), and RPE (mean difference: 0.39; 95% confidence interval: [0.04, 0.73]) during time trials, as well as post time-trial blood lactate concentration (mean difference: 1.06 mmol·L-1; 95% confidence interval: [0.31, 1.80 mmol·L-1]). In conclusion, SP supplementation has no significant effects on submaximal physiological responses or 20 km time-trial performance.
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The effects of a caffeine-like supplement, TeaCrine®, on muscular strength, endurance and power performance in resistance-trained men.
Cesareo, KR, Mason, JR, Saracino, PG, Morrissey, MC, Ormsbee, MJ
Journal of the International Society of Sports Nutrition. 2019;(1):47
Abstract
BACKGROUND TeaCrine® is the synthetic version to naturally occurring theacrine (1, 3, 7, 9-tetramethyluric acid) found in the leaves of Camellia kucha tea plants. A few studies have examined the effects of TeaCrine® on cognitive perception, but no research exists examining its effects on resistance exercise performance. The purpose of this study was to determine the efficacy of TeaCrine®, a caffeine-like compound, on maximal muscular strength, endurance, and power performance in resistance-trained men. METHODS Twelve resistance-trained men participated in a randomized, double-blind, cross-over designed study. Each participant performed one-repetition maximum (1RM) bench press, 1RM squat, bench press repetitions to failure (RTF) at 70% 1RM, squat RTF at 70% 1RM, and 2-km rowing time trial 90 min after consumption of: (1) Caffeine 300 mg (CAFF300); (2) TeaCrine® 300 mg (TEA300); (3) TeaCrine® + Caffeine (COMBO; 150 mg/150 mg); (4) Placebo 300 mg (PLA). Power and velocity were measured using a TENDO Power Analyzer. Visual analogue scales for energy, focus, motivation to exercise, and fatigue were administered at baseline and 90 min post-treatment ingestion (pre-workout). Rating of perceived exertion was assessed after bench press RTF and squat RTF. RESULTS There were no differences between groups for 1RM, RTF, and power in the bench press and squat exercises. Only CAFF300 resulted in significant increases in perceived energy and motivation to exercise vs. TEA300 and PLA (Energy: + 9.8%, 95% confidence interval [3.3-16.4%], p < 0.01; + 15.3%, 95% CI [2.2-28.5%], p < 0.02; Motivation to exercise: + 8.9%, 95% CI [0.2-17.6%], p = 0.04, + 14.8%, 95% CI [4.7-24.8%], p < 0.01, respectively) and increased focus (+ 9.6%, 95% CI [2.1-17.1%], p = 0.01) vs. TEA300, but there were no significant differences between CAFF300 and COMBO (Energy + 3.9% [- 6.9-14.7%], Focus + 2.5% [- 6.3-11.3%], Motivation to exercise + 0.5% [- 11.6-12.6%]; p > 0.05). CONCLUSION Neither TEA300, CAFF300, COMBO, or PLA (when consumed 90 min pre-exercise) improved muscular strength, power, or endurance performance in resistance-trained men. Only CAFF300 improved measures of focus, energy, and motivation to exercise.
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Photobiomodulation therapy before futsal matches improves the staying time of athletes in the court and accelerates post-exercise recovery.
De Marchi, T, Leal-Junior, ECP, Lando, KC, Cimadon, F, Vanin, AA, da Rosa, DP, Salvador, M
Lasers in medical science. 2019;(1):139-148
Abstract
This study aimed to analyze PBMT effects on futsal player's performance and recovery in a non-controlled field environment. It is a randomized, triple-blinded, placebo-controlled, crossover clinical trial. The research included six professional athletes and in each match phototherapy treatments were performed before matches (40 minutes), blood samples were collected before treatments, and samples immediately after the end of the matches and 48 h after. Furthermore, videos were analyzed to quantify the time athletes spent on the pitch and the distance they covered. PBMT was performed at 17 sites of each lower limb (40 mins before matches), employing a cluster with 12 diodes (4 laser diodes of 905 nm, 4 LEDs of 875 nm, and 4 LEDs of 640 nm, 30 J per site). The performance of the athlete could be quantified considering the time on the pitch and the distance covered; the biochemical markers evaluated were creatine kinase, lactate dehydrogenase, blood lactate, and oxidative damage to lipids and proteins. PBMT significantly increased the time of staying in the pitch and a significant improvement in all the biochemical markers evaluated. No statistically significant difference was found for the distance covered. Pre-exercise PBMT can enhance performance and accelerate recovery of high-level futsal players.
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Caffeine Increased Muscle Endurance Performance Despite Reduced Cortical Activation and Unchanged Neuromuscular Efficiency and Corticomuscular Coherence.
Franco-Alvarenga, PE, Brietzke, C, Canestri, R, Goethel, MF, Viana, BF, Pires, FO
Nutrients. 2019;(10)
Abstract
The central and peripheral effects of caffeine remain debatable. We verified whether increases in endurance performance after caffeine ingestion occurred together with changes in primary motor cortex (MC) and prefrontal cortex (PFC) activation, neuromuscular efficiency (NME), and electroencephalography-electromyography coherence (EEG-EMG coherence). Twelve participants performed a time-to-task failure isometric contraction at 70% of the maximal voluntary contraction after ingesting 5 mg/kg of caffeine (CAF) or placebo (PLA), in a crossover and counterbalanced design. MC (Cz) and PFC (Fp1) EEG alpha wave and vastus lateralis (VL) muscle EMG were recorded throughout the exercise. EEG-EMG coherence was calculated through the magnitude squared coherence analysis in MC EEG gamma-wave (CI > 0.0058). Moreover, NME was obtained as the force-VL EMG ratio. When compared to PLA, CAF improved the time to task failure (p = 0.003, d = 0.75), but reduced activation in MC and PFC throughout the exercise (p = 0.027, d = 1.01 and p = 0.045, d = 0.95, respectively). Neither NME (p = 0.802, d = 0.34) nor EEG-EMG coherence (p = 0.628, d = 0.21) was different between CAF and PLA. The results suggest that CAF improved muscular performance through a modified central nervous system (CNS) response rather than through alterations in peripheral muscle or central-peripheral coupling.
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Beta-alanine supplementation improves isometric, but not isotonic or isokinetic strength endurance in recreationally strength-trained young men.
Bassinello, D, de Salles Painelli, V, Dolan, E, Lixandrão, M, Cajueiro, M, de Capitani, M, Saunders, B, Sale, C, Artioli, GG, Gualano, B, et al
Amino acids. 2019;(1):27-37
Abstract
β-Alanine (BA) supplementation may be ergogenic during high-intensity exercise, primarily due to the buffering of hydrogen cations, although the effects of beta-alanine supplementation on strength endurance are equivocal. The aim of the study was to determine the effects of 4 weeks of beta-alanine supplementation on skeletal muscle endurance using a battery of performance tests. This study employed a parallel group, repeated measures, randomised, double-blinded and placebo-controlled design. Twenty recreationally strength-trained healthy males completed tests of isotonic strength endurance (repeated bench and leg press), along with tests of isometric and isokinetic endurance conducted using an isokinetic dynamometer. Tests were performed before and after a 4 week intervention, comprising an intake of 6.4 g day-1 of BA (n = 9) or placebo (maltodextrin, n = 11). Time-to-exhaustion during the isometric endurance test improved by ~ 17% in the BA group (p < 0.01), while PL remained unchanged. No significant within-group differences (p > 0.1) were shown for any of the performance variables in the isokinetic test (peak torque, fatigue index, total work) nor for the total number of repetitions performed in the isotonic endurance tests (leg or bench press). Four weeks of BA supplementation (6.4 g day-1) improved isometric, but not isokinetic or isotonic endurance performance.
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No Benefit of Ingestion of a Ketone Monoester Supplement on 10-km Running Performance.
Evans, M, McSwiney, FT, Brady, AJ, Egan, B
Medicine and science in sports and exercise. 2019;(12):2506-2515
Abstract
PURPOSE Preexercise ingestion of exogenous ketones alters the metabolic response to exercise, but effects on exercise performance have been equivocal. METHODS On two occasions in a double-blind, randomized crossover design, eight endurance-trained runners performed 1 h of submaximal exercise at approximately 65% V˙O2max immediately followed by a 10-km self-paced time trial (TT) on a motorized treadmill. An 8% carbohydrate-electrolyte solution was consumed before and during exercise, either alone (CHO + PLA), or with 573 mg·kg of a ketone monoester supplement (CHO + KME). Expired air, HR, and RPE were monitored during submaximal exercise. Serial venous blood samples were assayed for plasma glucose, lactate, and β-hydroxybutyrate concentrations. RESULTS CHO + KME produced plasma β-hydroxybutyrate concentrations of approximately 1.0 to 1.3 mM during exercise (P < 0.001), but plasma glucose and lactate concentrations were similar during exercise in both trials. V˙O2, running economy, respiratory exchange ratio, HR, and RPE were also similar between trials. Performance in the 10-km TT was not different (P = 0.483) between CHO + KME (mean, 2402 s; 95% confidence interval, 2204-2600 s) and CHO + PLA (mean, 2422 s; 95% confidence interval, 2217-2628 s). Cognitive performance, measured by reaction time and a multitasking test, did not differ between trials. CONCLUSIONS Compared with carbohydrate alone, coingestion of KME by endurance-trained athletes elevated plasma β-hydroxybutyrate concentrations, but did not improve 10-km running TT or cognitive performance.